Process for producing a crystalline zeolite

ABSTRACT

Faujasitic-type crystalline zeolites X and Y are produced. In one embodiment, sodium sulfide is added to the reaction mixture as a source of sodium and as a buffer. The buffering action of the sodium sulfide provides the basicity required to maintain the alumina hydrate component of the reaction mixture in solution but not a basicity whereby zeolite crystallization is retarded. In another embodiment, a nucleating mixture having the formula 310Na2S: 5-15 Na2O: 5-50 SiO2: 0.4-4.0 Al2O3: 50-500H20 is added to the reaction mixture to promote crystall;ne zeolite formation.

United States Patent [191 Elliott, Jr.

[ PROCESS FOR PRODUCING A CRYSTALLINE ZEOLITE [75] Inventor: Curtis H. Elliott, Jr., Baltimore, Md.

[73] Assignee: W. R. Grace & Co., New York,

[22] Filed: May 4, 1971 [21] Appl. No.: 140,249

[56] References Cited UNITED STATES PATENTS 4/1959 Milton ..423/328 4/1964 Breck ..423/323 Jan. 29, 1974 3,574,538 4/1971 McDaniel et al. 423/329 Primary Examiner-Edward J. Meros Attorney, Agent, or FirmW. R. Grace & Co.

[57] ABSTRACT Faujasitic-type crystalling zeolites X and Y are produced. In one embodiment, sodium sulfide is added to the reaction mixture as a source of sodium and as a buffer. The buffering action of the sodium sulfide provides the basicity required to maintain the alumina hydrate component of the reaction mixture in solution but not a basicity whereby zeolite crystallization is retarded. In another embodiment, a nucleating mixture having the formula 3-l0Na S: 515 Na O: 5-50 SiO 0.4-4.0 A1 0 50500H 0 is added to the reaction mixture to promote crystall;ne zeolite formation.

5 Claims, No Drawings PROCESS FOR PRODUCING A CRYSTALLINE ZEOLITE This invention relates to zeolite X and zeolite Y zeolite molecular sieves produced using a sulfide as a principal reactant. This invention further relates to a sodium sulfide containing nucleating mixture which provides nucleation or seeding centers for the crystallization of ten angstrom molecular sieves.

The molecular sieves to which this invention is directed are crystalline zeolite molecular sieves having an effective pore diameter of 10 angstroms. Such l angstrom sieves have also become known as Zeolite X and Zeolite Y. Zeolite X has been set out in U. S. Pat. No. 2,882,244, and Zeolite Y in U. S. Pat. No. 3,130,007. Zeolite X and Zeolite Y are tradename designations of the Linde Division of the Union Carbide Corporation, with Z-14 and Z-l4 HS being tradename designations of the Davison Division of W. R. Grace & Company. These zeolite materials have found considerable use as adsorbents, components in petroleum cracking catalysts, in hydrocracking catalysts and in hydrotreating catalysts. As adsorbents, these zeolites are either used by themselves or in combination with clay binders. In use as cracking catalysts, these zeolites are usually exchanged with hydrogen, ammonia, rare earth or transition metal ions and incorporated into an oxidic matrix, usually a silica-alumina matrix, with or without a clay binder. The zeolite component in such catalysts usually comprises about to percent by weight of the total catalyst.

As noted above, Zeolite X and Zeolite Y are both essentially 10 angstrom crystalline molecular sieves. Principal differences between these sieves, however, are in the silica/alumina ratios and X-ray pattern. Zeolite X has a ratio in the range of about 2 up to 3, and Zeolite Y of from about 3 to 6. The general formula of sodium Zeolite X is Na O: 2.5 i 0.5 SiO A1 0 1-8 H O with the general formula of Zeolite Y being Na O: 3-6 SiO A1203: 1-9

There are many prior art techniques for producing Zeolite X and Zeolite Y molecular sieves. One method comprises the addition of a caustic solution, and/or a silicate solution and/or an aluminate solution to metakaolin clay followed by the hydrothermal conversion of the meta-kaolin clay to the crystalline zeolite. Another method comprises the reaction of a silicate solution and an aluminate solution in reactant ratios effective to produce these zeolites. There also exist other methods which are too numerous to outline here. However, none of these techniques have used a sulfide route to produce ten angstrom molecular sieves. In this invention, I have discovered that Zeolite X and Zeolite Y (also known as Z-l4 and Z-l4 HS zeolites respectively) can be produced by using a sulfide such as sodium sulfide in place of at least part of the caustic component in producing crystalline zeolites. I have also discovered that ten angstrom crystalline molecular sieves can be very efficiently produced using a sodium sulfide nucleating mixture whereby the aging step can be eliminated. These sodium sulfide nucleating mixtures have been found to be very effective in promoting l0 angstrom zeolite production using the sulfide technique of this invention, as well as from conventional sodium aluminate and sodium silicate solutions, or in hydrothermal clay conversions.

It is, therefore, an object of this invention to set out a sulfide method for producing Zeolite X and Zeolite Y crystalline zeolitic molecular sieves.

It is additionally an object of this invention to set out a sulfide zeolite nucleating mixture and a method of producing this solution.

It is further an object of this invention to efficiently form Zeolite X and Zeolite Y crystalline zeolites by the addition of a sulfidic zeolite nucleating mixture to an aluminate and silicate solution mixture whereby massive numbers of nucleation centers are rapidly formed.

It is another object of this invention to produce Zeolite X and Zeolite Y crystalline zeolites by the addition of a sulfidic nucleating mixture to an aluminate, silicate and sulfide solution mixture whereby massive numbers of nucleation centers are rapidly formed.

In brief summary, my invention comprises the forming of ten angstrom crystalline zeolite molecular sieves by either of two embodiments. A first embodiment comprises forming these zeolites fr'om aluminate and silicate solutions wherein a substantial part of the caustic component has been replaced by sodium sulfide. A second embodiment of this invention comprises the use of a sodium sulfide nucleating mixture to form nucleation centers in a conventional caustic sodium silicate and sodium aluminate reaction mixture, in the hydrothermal conversion of clay to zeolite, or in the formation of zeolites from a sulfidic solution wherein sodium sulfide replaces a substantial part of the caustic component in the sodium silicate and sodium aluminate reactant solutions.

In more detail, my invention comprises the preparation of Zeolite X and Zeolite Y zeolite molecular sieves by the partial substitution of sodium sulfide or sodium sulfide yielding material for caustic in the original reaction mixture to obtain buffering action in this mixture. These molecular sieves are very effectively produced by forming a sodium aluminate-sodium sulfide solution, followed by the addition of a sodium silicate solution to this mixture. The buffering action of the sodium sulfide provides the basicity required to dissolve the alumina hydrate component and maintain this component in solution, but is not of a basicity whereby zeolite crystallization is retarded. At high basicity levels, the zeolite nuclei are constantly being redissolved as they are formed thereby generally requiring long aging times to provide sufficient nuclei for effective crystallization. This invention solves this problem at least in part by utilizing both the basicity and buffering ability of the sulfide ion. While the hydroxylion is highly basic, it does not possess the buffering capability of the sulfide ion. A principal result of this property of the sulfide ion is that the 10 angstrom sieves produced have a more sharply defined X-ray structure and a higher surface area. The molecular ratios of'components to effectively produce a Zeolite X is in the range of and the effective molecular ratio of components to produce Zeolite Y are in the range of This combination is then mixed or otherwise converted to a homogenous state, aged and crystallized. The aging step is essentially allowing the mixture to stand at a temperature of 15 to 75 C and preferably about room temperature for from about 2 to 30 hours. During this aging, crystallization nuclei form so that the mixture can subsequently be crystallized. Crystallization comprises heating this aged solution mixture at from about 40 to 95 C for from 1 to 20 hours. During this heating, thezeolite crystals form and grow. The crystalline zeolite is then separated from the remaining liquor, washed, dried and activated.

A further embodiment of my invention comprises the adding of a sulfidic zeolite nucleating mixture to the above reaction mixture combination of sodium silicate, sodium aluminate and sodium sulfide. This nucleating mixture has the general formula 3-10 Na S:-15 Na O:5-50 SiO :0.14.0 Al O :50-500 H O. This nucleating mixture is produced by admixing a sodium aluminate and a sodium sulfide solution followed byadmixing a sodium silicate solution and incubating the resultant admixture. A useful incubating time is 24 hours. This nucleating mixture is added so as to be in a concentration of about 2 to percent by weight of the reaction mixture. By the addition of this mixutre, the aging step can be considerably decreased or even eliminated. Further in the crystallization step, the period of heating can be decreased to 0.5 to 4 hours. By the use of this nucleation mixture, nucleation centers are provided in the sodium aluminate, sodium silicate, sodium sulfide solution mixture. Therefore, since the function of the aging step is accomplished by this nucleation mixture, an aging is not required.

Another embodiment of my invention comprises the use of this'sulfidic zeolite nucleating mixture with conventional sodium silicate and sodium aluminate mixtures so as to supply the reaction mixtures generally used to form these 10 angstrom zeolites have the following molecular ratios of components are as follows:

SlOg/AlgOg H O/Na O greater than and Slo /A1 0 3.5-

Na OIAI O, 2.5-10

H,O/Na O greater than 15 The sulfidic zeolite nucleating mixture is added to these reactant mixtures usually so as to be in a concentration of from about 2 to 10 percent by weight. After the mixicate and aluminate solutions, with or without sodium sulfide. These nucleating mixtures may be effectively used in the hydrothermal conversion of clays to zeolites or in any other technique where an amorphous silicaalumina is converted to a crystalline zeolitic molecular sieve.

The following examples are set out to further amplify the present invention.

EXAMPLE I This example sets out a method for producing molecular sieve crystallization nucleating mixtures containing substantial amounts of Na' S. A solution containing 200 grams of Na S9 H 0, grams of NaOH and 297 grams of H 0 was prepared and heated to 200 F. Then 26 grams of C-31 aluminum hydrate (65 percent Al- O was dissolved therein. After dissolving was completed, the solution was cooled to F.

To the above Na S reactant mixture was added 685 grams of 28 percent Na SiO solution with thorough mixing.

After the two solutions were well mixed, the resultant product was allowed to incubate at room temperature for 24 hours. The resultant mole ratios of the components are:

l Al O 5.0 Na S- 10.7 Na O 14.9 S10 319 H O EXAMPLE 11 This example illustrates the formation of faujasite using the nucleating mixture ofExample l.

A faujasite precursor slurry is formed by dissolving 53.1 g. of NaOH in 70 g. of H 0, followed by the addition of 74 g. of C-31 alumina hydrate (65 percent Al 0 This mixture is boiled until the alumina hydrate is dissolved. 220 g. of H 0 is then added, and the mix cooled to 100 F. This cooled solution is then added to 1,240 g. of 31.2 Be sodium silicate (21.7 percent SiO 6.7 percent Na O) with continuous stirring to assure a uniform slurry.

This faujasite precursor slurry is then divided into two equal portions and treated as follows:

Portion A the slurry was heated to 210-215 F and maintained at this temperature without stirring for 6 hours, quenched, filtered, water washed and dried at 1,000 F for 1 hour Portion B the slurry was activated by adding the molecular sieve nucleating mixture of Example 1 taking care to assure uniform dispersion of the nucleation centers throughout the slurry mass. The activated slurry was then heated to 210-215 F and maintained at this temperature without stirring for 6 hours, quenched, filtered, well-water washed and dried at 1,000 F for 1 hour.

The results are as follows:

Portion A (as is slurry) Portion B (sulfide nuclei activated) X-ray Crystallinity-amorphous 83% of Zeolite Y Cell Size-amorphous 24.71A Surface Area 626 M /g Thus,it is obvious that the sulfide molecular sieve nucleations centers energize the crystallization of the bulk faujasite slurry. The nuclei added in this experiment equaled 5 percent of the total mass on an A1 0 basis (comparison of respective alumina contents).

6 EXAMPLE I The data and results are reported in Table I. This example illustrates the use of sodium sulfide in TABLE I place of part of the NaOH component in the formation R of Zeolite X. The runs i, ll and III further illustrate that 5 l H the sodium sulfide content can be varied. Reaction Mole Ratio I 240 grams of sodium sulfide (Na S-9 H O) was dis- 2. g L0 solved in 312 ml. of H 0. 157 grams of alumina hy- 2 6 2:;

drate was then dissolved in this sodium sulfide solu- Naas 1.0 1.4

tion. 373 grams of 50 percent NaOH was then 10 X Ray gf g added. This solution was diluted with 976 ml. of Pe m f st ard 130 125 112 H 0 and cooled. This is designated as solution A. Surface Area 7 M lg 841 7o9 673 664 grams of 40 Be sodium silicate is diluted with ]1,244 ml; of This isdezignatfed SolutionlB. 810- What is claimed lmons an are mlxe to orm a mo ecu at 1. A method for producing a crystalline faujasite zeosieve reactant precursor slurry.

. lite selected from the group consisting of Zeolite X and This slurry is aged 22 hours at room temperature, and Zeolite Y com risi heated for 12 hours at 200212 F to cause crysf p d t h n h tallization. This slurry is then filtered and water ormmgldregc an a mix ure avmg 7586mm yt e washed to a pH of 10.54 L formulation in terms of molecular ratios of compou 336 grams of sodium sulfide (Na S-9 H O) was dissolved in 478 ml. of water. 157 grams of C-31 alumina was then dissolved in this sodium sulfide solusioz/Alzo3 2,440

tion. 310 grams of 50 percent NaOH was then Nap/A t s 25-10 added. This solution was diluted with 810 m1. of so/N220 great H 0 and cooled. This is designated as solution A.

b. dispersing within said reactant admixture a zeolite 664 grams of 40Be sodium silicate was diluted with nucleatmg mixture consisting essentially of 1 1,244 ml. n 0. This is designated Solution B. Solu- 3 Na2S=5i15 19212010140 Allow 507500 Sald tions A and B are mixed to form a molecular Sieve nucleatmg mixture formed from an incubated solureacmnt precursor Slurry tion mixture of sodium aluminate, sodium sulfide, This slurry is aged 22 hours at room temperature, n and f f slhcate; o o

and heated for 12 hours at 200-212 F to cause heatmg thls mass at from 40 to 100 C for from crystallization l-2O hours and forming said faujasite zeolite, the This slurry is then filtered and water washed to a pH species of faulaslte Zeollte dependmg on the molecf 5 1 ular ratio of components of said formulation. 1 157 grams f .31 Alumina was dissolved in 535' 2. A method as in claim 1 wherein said zeolite nuleatgrams of 50 percent NaOH. 1,288 ml. of H 0 were g mixture has the compositlon added and the solution cooled, 40 5.0 Na S:lO.7 N8 OZl4.9 S|O2:Al203:3 l9 H2O.

This is d ignat d S l ti A, 3. A method as in claim 1 wherein said crystalline ze- 664 grams of 40 Be sodium silicate is diluted with Olite is Washed, dried and activatedl,244 ml, HO. This is designated Soluti n B, 4. A method as in claim 1 wherein said nucleating Solution A is mixed with Solution B to form a molecumixture is added so as to be in a concentration of about lar sieve reactant precursor slurry. 2 to 10 percent by weight of the reaction mixture.

This slurry is aged 22 hours at room temperature and 5. A method as in claim 1 wherein prior to step (c),

heated for 12 hours at 200-212 F to cause crysthe mixture of step (b) is agedat 15 to C for 0.5

tallization. This slurry it then filtered and water to 4 hours.

washed to apH of 10.5-11.

3 .789 107 Dated Januany 29 r 1974 I 1nventor(s) Curtis H- Elliott, Jr-

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In Claim 1, paragraph b, amend the formula to read:

..-- 3-10 Na S: 5-15 Na O: 5-50 510 0,1-4 0 1 0 Signed and sealed this 16th day of .July 197 (SEAL-)7 Attest:

MCCOY IYL GIBSON, JR. v c. MARSHALL DANN Attestlng Officer Commissioner of Patents 

2. A method as in claim 1 wherein said zeolite nuleating mixture has the composition 5.0 Na2S:10.7 Na2O:14.9 SiO2:Al2O3:319 H2O.
 3. A method as in claim 1 wherein said crystalline zeolite is washed, dried and activated.
 4. A method as in claim 1 wherein said nucleating mixture is added so as to be in a concentration of about 2 to 10 percent by weight of the reaction mixture.
 5. A method as in claim 1 wherein prior to step (c), the mixture of step (b) is aged at 15* to 75* C for 0.5 to 4 hours. 